Recent global warming unprecedented in 1,300 years

A new scientific study shows that temperatures in the Northern Hemisphere have been changing over time, but the increase during the past few decades is bigger than anything in at least 1,300 years.The study was published by the National Academy of Sciences, its conclusion is that temperature increased and decreased a little over the centuries, but the changes were small enough that the line was roughly flat, like the stick of a horizontal hockey stick. Climatologist Michael Mann , director of the Earth System Science Center at Pennsylvania State University says that the study in which he conducted “establishes further evidence that the recent warming isn’t just part of a typical cycle. In his study they took data from other natural sources of clues about past climate: coral reefs, ice cores and lake and cave sediments. Mann said there was a burst of about 0.3 degrees from about 1900 to 1950. Then, in the 1950s to 1970s, temperatures were flat or showed a slight cooling, because heavy particle pollution, which has a cooling effect, masked the heating effect of greenhouse gases, Mann said. Another, larger increase of temperature has been recorded in the past 30 years, he said, due largely to the increase of greenhouse gases.


Many have down played the studies done to show the warming of the planet because they don't believe that the typical studies which use tree ring samples are accurate. Mann has debased the argument used by many who still believe that global warming isn't being influenced by man which is just another good step in the right direction which need to be followed by many more advancing steps.

http://www.dailytimes.com.pk/default.asp?page=2008\09\29\story_29-9-2008_pg6